1. Field of the Invention
The present invention relates to a printed wiring board where a semiconductor element is mounted on its upper surface while another printed wiring board is mounted thereon.
2. Description of Background Art
In Japanese Laid-Open Patent Publication No. 2012-9586, a solder-resist layer is filled between pads for peripheral mounting, and solder is used as a spacer to maintain clearance between an IC chip and a printed wiring board. Also, in Japanese Laid-Open Patent Publication No. 2012-9586, the thickness of a solder-resist layer is reduced by using a sandblasting method. The entire contents of this publication are incorporated herein by reference.